Powder feed and metering device for flame spray guns



June 23, 1964 w $|EBE|N T 3,138,298

POWDER FEED AND METERING DEVICE FOR FLAME SPRAY GUNS Filed July 19, 19612 Sheets-Sheet 1 a 9 M1 vs I --2/ 6 I4 I57 l6 Q -5/ C W INVENTORS WALTERA. S/EBE/N ANT HON Y J ROTOL/CO FLOYD GREEN GRASS T'TORNEYS June 23,1964 w. A. SIEBEIN ETAL 3,138,298

POWDER FEED AND METERING DEVICE FOR FLAME SPRAY GUNS Filed July 19, 19612 Sheets-Sheet 2 INVENTORS WALTER ,4. S/E'BE/N ANTHONY J. ROTOL/CO FLOVD GREENGEASS BY fiw b xg y i ATTORN United States Patent 3,138,293POWDER FEED AND METERING DEVHIE FOR FLAME SPRAY GUNS Walter A. Siehein,Smithtown, Anthony J. Rotolico, Lynbrook, and Floyd Greengrass, DeerPark, N.Y., assignors to Metco lino, Westbury, N.Y., a corporation ofNew Jersey Filed July 19, 1961, Ser. No. 125,267 3 Claims. (Cl. 222-139)This invention relates to a powder feed and metering device for flamespray guns.

In flame spray guns heat-fusible material, as for example a heat-fusiblemetal or ceramic, is passed into a heating zone Where the same is heatedto at least heatsoftened condition and propelled, as for example, ontothe surface to be coated. The heat in the heating zone is generallyprovided by a combustion flame and in newer devices may be formed from aplasma flame generated by passing a plasma-forming gas in contact with aconstricted electric arc.

In flame spray guns of the powder type, the heat-fusible material is fedinto the heating zone, as for example, the combustion flame or plasmaflame, in the form of a powder as for example having a particle sizebelow about 80 and preferably below about 140 US. Standard Screen size.

The powder is generally fed into the combustion or plasma flame bygravity flow or entrained in a carrier gas which is injected into theflame.

In order to obtain high quality coatings of a given type and for a givenpurpose, it is necessary to accurately control the rate of powder feedinto the flame and to maintain the same constant for given sprayconditions.

The accurate metering and uniform and consistent control of the powderfeed to the gun has presented difficulties as the rate, ease, anduniformity of powder flow, as for example by gravity through a givenconduit will vary widely depending on the size, shape, and type of theindividual particles and various ambient and physical conditions which,as a practical matter, cannot be accurately controlled during operation.Furthermore, even two different batches of powder which are commerciallyconsidered identical may flow differently under identical conditions.

One object of this invention is a device which allows the accuratemetering and feed of heat-fusible powder, such as metal or ceramicpowder, to a flame spray gun.

This and still further objects will become apparent from the followingdescription read in conjunction with the drawings in which:

FIG. 1 is a front elevation partially in vertical section of anembodiment of a powder feed and metering device in accordance with theinvention;

FIG. 2 is a side elevation, partially in section of the device shown inFIG. 1;

FIG. 3 is a cross section of a portion of the device shown in FIG. 2;and

FIG. 4 is a plan view partially in section of the plunger of the deviceof FIGS. 1 and 2.

The powder feed and metering device in accordance with the inventionutilizes a gravity powder feed from a supply leading into a positivefeed mechanical conveyor driven by a variable speed drive which, inturn, feeds into a conveying gas stream leading to the flame spray gun.

Referring to the embodiment showing in the drawing, 1 represents ahousing, as for example constructed of metal or the like and providedwith the horizontal cylindrical bore 2 in which is inserted the cylinderliner 3 forming a cylinder having a substantially horizontal axis. Thecylinder is enclosed at its rear end by the back plate 4 of the cylinderliner 3 and enclosed at its front end by means of the removable cover 5.The cover 5 is provided with the bearing sleeve 6 and may be snapped inand out of place by means of the spring loaded plungers 7 and 8 engagingthe annular shoulder 9 (FIG. 3). Rotatably positioned in the cylinder isthe metering gear 10. As may best be seen from FIG. 3, the metering gear10 is seated on the bushing 11, which, in turn, is threaded on androtates with the shaft 12. The bushing 11 is provided with a disc 13 andthe gear 10 is sandwiched between this disc 13 and a rear disc 14 whichis screwconnected to the disc 13 by means of the screws 15. The discs 13and 14 are provided with the O-ring seals 16 which move in sealingcontact with the cylinder liner 3. The entire unit consisting of theshaft 12, the gear 10, the bushing 11, the discs 13 and 14, rotates withthe seals 16 in contact with the cylinder liner 3 while the cylinderliner is secured against rotation by means of the set screws 17 and 18.The shaft 12 is provided with the cross pin 19 at its rear end andsupported by the bearing 6 and a bearing formed by the back plate 4 ofthe cylinder liner 3. The cross pin 19 engages in a slot 20 in the drivecoupling 21 which is secured to the end of the drive shaft 22' whichrotates in the bearings 23 and 24 and which is provided with the seal25. The shaft 22 is rotated by means of the worm gear drive 26, 27. Theshaft of the worm gear 27 is driven by means of the gear 28 which, inturn, is driven by the gear 29, secured to the shaft 30 of the motor 31.The motor 31 is a DC. electrical motor of conventional construction witha speed that can be varied, as for example, by means of the control boxdiagrammatically shown as 32. The motor 31 is preferably a directcurrent, field-controlled DC. motor using a- Thyratron control in whichthe back is used to govern the motor speed.

It is, of course, understood that in place of the motor 31 and drivetrain, as shown, any other known or conventional drive means whose speedmay be controlled may be used for rotating the metering gear 10.

A gravity flow passage 33 leads through the cylinder wall and cylinderliner in communication with the teeth of the metering gear 10. The upperend of the gravity flow passage 33 is provided with the funnel-shapedbushing 34.

Mounted on top of the housing 1 on each side of the gravity flow passage33 are the posts 35 and the clips 36. The clips 36 are screwed directlyto the housing by means of a screw 37 extending through the center ofthe posts 35 and are attached to the cup-shaped inserts 38, secured tothe clips, by means of the bowed spring washers 39. Due to thisarrangement the clips may be flexed upwardly and downwardly a limitedextent in a spring-like manner.

A hopper arrangement for powder is mounted above the housing. The hopperarrangement consists of the hopper container proper 40 and the base unit41 which is provided with an automatic shut-off valve arrangement. Thebase unit 41 is provided with the central gravity flow discharge opening42 extending through the bushing 43 and rubber tube 44 in communicationwith the gravity feed passage 33. A breather passage 45 extends throughthe base unit in communication with the ambient atmosphere. Thisbreather passage is provided with the porous plug 46 which allows thepassage of gas but not powder therethrough. This porous plug may, forexample, be made of sintered metal. The base unit 41 is also providedwith the lateral bore 47 in which is positioned the axially slidableplunger 48. The plunger, as may best be seen from FIG. 4, is providedwith the rod shaped end 49 and the two connecting pins 50 which extendon either side of the tube 44 and are connected with the clampmember 51.The clamp member 51 is spring-loaded by means of the springs 52. Whenthe rod-shaped end 49 is free, the springs 52 will axially move theplunger so that the clamp member 51 will squeeze the tube 44 shutagainst the pin 53, so that the plunger with the tube 44 forms anautomatic closure valve. The spring 52 is retained in place by means ofthe screw plug 54. The base unit is provided with the slots 55 and itsbottom portion extending past these slots at right angles thereto issmaller in diameter than the distance between the tips of the clips 36.By rotating the hopper arrangement 90 degrees, the clips 36 will bedisengaged from the slots 55 and the unit may be lifted oil from thehousing. In this position, the plunger is free to move under theinfluence of the spring so that the tube 44 is pinched shut and thehopper automatically closed. To reposition the hopper in place, the sameis inserted in the same manner as for its removal and then rotated 90degrees. The rotation causes the engagement of the clips 36 in the slots55 and as the end 49 of the plunger engages a post 35, the plunger isaxially moved by the pressure contact with the post compressing spring52 and releasing the tube 44. A small indent or opening 56 is providedon the inner wall of the post 35 in which the end from the plunger 49engages when the hopper is in position. This acts as a detent and thecorrect positioning of the hopper may be noted by the feel and by aclick. The hopper proper 40 is screwfitted into the base unit by meansof the threads 57. These threads correspond in pitch and size to thethreads for a cap on a commercial can for flame spray powder so that itis possible in place of the hopper 40, to screw the base unit directlyon to a powder can in place of its top. In this manner, by providingseveral base units on diflerent powder cans, the type of powder that isbeing fed through the device may be very quickly and convenientlychanged by merely snapping the entire powder can with the base unit fromthe device and replacing it in an equally simple manner by a differentpowder can with a different but identically constructed base unit.

A gas flow passage 58 extends horizontally through the housing below thecylinder 2. A coupling 59 for a gas line is screwed into this passage at61 and is provided with a jet opening 60 directed into the passage. Afurther coupling 62 for a gas flow line is connected to the oppositeside of the gas flow passage 58 by means of the threads 63. The coupling62 is provided with an inlet passage 64 which is slightly conicallytapered. A vertical flow passage 65 communicates the lower end of theinterior of the cylinder liner 3 with the portion of the gas flowpassage 58 between the jet 60 and inlet 64. A vibrator, such as anelectrical vibrator of conventional construction 66, may be secured intothe bottom of the housing.

In operation, a gas line or a carrier gas as is conventionally in aflame spray gun is connected to the coupling 59. In connection with aflame spray gun utilizing a combustion flame, the gas may be one of thecomponents of the combustible mixture fed to the gun, as for example,oxygen, acetylene, hydrogen, or the like. In connection with a plasmaflame spray gun, the carrier gas may be the gas used as a plasma-forminggas or any other gas, as for example inert gas, etc. A flexible conduit,such as a hose, is connected between the coupling 62 and the powder feedinlet of a flame spray gun as for example the inlet for powder leadingthrough the gun nozzle as described in copending application Serial No.126,827, filed July 14, 1961.

The powdered heat-fusible material to be sprayed, as for examplepowdered metal or ceramic material, is positioned in the hopper 40 or inplace of the hopper 40 a can of the powder is directly screwed to thebase unit 41. With the base unit removed from the device, the plunger 49and particularly the clamp 51 thereof will squeeze tube 44 shut tightagainst the pin 53 so that the discharge opening through the containeris automatically sealed. The container is positioned by positioning thedischarge opening in the plate 67 in the bottom of the base unit inalignment with the opening 33 so that the indented portion in this baseplate 67 mates with the bushing 34. The container with the base unit isthen rotated 90 degrees and secured in place by the clips 36 engaging inthe slots 55. The valve is automatically opened as the end 49 of theplunger engages post sliding the plunger axially to the position shownin FIG. 1 until the end engages in the opening 56.

The powder will, therefore, flow, by gravity, through the opening 42 andtube 44 into the gravity flow passage 33 and into the cylinder betweenthe teeth of the metering gear 10 which are positioned adjacent thegravity flow passage 33. The metering gear 10 is driven in the directionof the arrow by means of the motor 31 and the gear train as described.As the gear 10 rotates, it causes the positive feed of controlledquantities of powder between its teeth to the passage 65 dumping thepowder into this passage where it flows into the gas flow passage 58.The carrier gas passes through the fitting 59 and jet openings 60, picksup and entrains this powder, carrying the same through the opening 64,fitting 62, and conduit to the flame spray gun. The gravity flowpassages should be large enough so that the flow rate therethrough underany conditions should be at least as large as the maximum conveying rateof the mechanical conveyor, i.e. the gear 10. The vibrator 66, ifoperated, will ensure that no bridging or jamming of the powder occursand will ensure even gravity flow thereof. Relief air to prevent thebuild-up of a vacuum in the container should the same be sealed at itsupper end is provided through the passage and plug 46. The amount ofpowder fed into the gas stream may be very accurately controlled andadjusted to the gas stream by control of the speed of rotation of thegear 10, as for example, by means of the control 32. The amount ofpowder fed into the gas stream may thus be extremely accuratelycontrolled independent of the gas stream flow rate and at an optimumvalue to a given flow rate and for given spray conditions.

The metering gear may be very simply removed for cleaning orreplacement, etc. by pulling the cap 5 from the device and unscrewingthe unit containing the metering gear from the shaft 12. The cylinderliner can also be replaced by simply backing off the set screws 17, 18and sliding the liner out. When reinserted, the proper alignment of theholes is ensured by a fit of the set screws 17 and 18 in their properrecesses.

While the invention has been described in detail with reference to thespecific embodiments shown, various changes and modifications which fallwithin the spirit of the invention will become apparent to the skilledartisan. The invention is, therefore, only intended to be limited by theappended claims or their equivalents wherein we have endeavored to claimall inherent novelty.

We claim:

1. A powder feed and metering device for a flame spray gun comprisingmeans defining a gravity flow passage for powder, a container for powderdetachably mounted above said gravity flow passage and having adischarge opening in communication with said gravity flow passage, aclosure valve for said discharge opening eomprising a flexible dischargetube forming a portion of said discharge opening, a plunger, springmeans normally biasing said plunger against said tube clamping said tubeshut, means for automatically opening said closure valve upon attachmentof said container above said gravity flow passage and for automaticallyclosing said closure valve upon detaching said container comprisingmeans adjacent said gravity flow passage for pressing said plunger torelease said tube when said container is attached, means defining a gasflow passage, a jet opening directed into said gas flow passage, meansfor passing a carrier gas for a flame spray gun through said jetopening, mechanical conveyor means for positive feed of controlledquantities of powder from said gravity flow passage to said gas flowpassage adjacent the outlet of said jet opening, and variable speeddrive means for driving said mechanical conveyor means at a controlledrate.

2. A powder feed and metering device for a flame spray gun comprising ahousing defining an enclosed cylinder with its axis extendingsubstantially horizontally, a gear rotatably positioned in said cylinderwith its teeth closely adjacent the cylinder wall, a gravity flowpassage extending into the upper portion of said cylinder, a gas flowpassage leading into a powder conduit for a flame spray gun, a passagefrom the lower portion of said cylinder leading into said gas flowpassage, means for passing a carrier gas through said gas flow passage,and variable speed drive means for rotating said gear, a base unit for apowder container detachably mounted above said housing and having adischarge opening in communication with said gravity flow passage, aportion of said discharge opening being defined by a flexible dischargetube, plunger means positioned adjacent said tube, spring means normallybiasing said plunger to clamp said tube shut and means mounted on saidhousing for engaging said plunger when said base unit is mounted thereonto force said plunger in a direction releasing said tube.

3. Powder feed and metering device according to claim 2 including abreather passage extending through said base unit communicating theinterior of a powder container mounted thereon with the ambientatmosphere, said breather passage containing a porous plug.

References Cited in the file of this patent UNITED STATES PATENTS2,011,133 Yoss Aug. 13, 1935 2,152,632 Cassiere Apr. 4, 1939 2,618,410Merow Nov. 18, 1952 2,820,670 Charlop et a1. Jan. 21, 1958 2,953,282Peterson Sept. 20, 1960

1. A POWDER FEED AND METERING DEVICE FOR A FLAME SPRAY GUN COMPRISINGMEANS DEFINING A GRAVITY FLOW PASSAGE FOR POWDER, A CONTAINER FOR POWDERDETACHABLY MOUNTED ABOVE SAID GRAVITY FLOW PASSAGE AND HAVING ADISCHARGE OPENING IN COMMUNICATION WITH SAID GRAVITY FLOW PASSAGE, ACLOSURE VALVE FOR SAID DISCHARGE OPENING COMPRISING A FLEXIBLE DISCHARGETUBE FORMING A PORTION OF SAID DISCHARGE OPENING, A PLUNGER, SPRINGMEANS NORMALLY BIASING SAID PLUNGER AGAINST SAID TUBE CLAMPING SAID TUBESHUT, MEANS FOR AUTOMATICALLY OPENING SAID CLOSURE VALVE UPON ATTACHMENTOF SAID CONTAINER ABOVE SAID GRAVITY FLOW PASSAGE AND FOR AUTOMATICALYCLOSING SAID CLOSURE VALVE UPON DETACHING SAID CONTAINER COMPRISINGMEANS ADJACENT SAID GRAVITY FLOW PASSAGE FOR PRESSING SAID PLUNGER TORE-